Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D501/00—Heterocyclic compounds containing 5-thia-1-azabicyclo [4.2.0] octane ring systems, i.e. compounds containing a ring system of the formula:, e.g. cephalosporins; Such ring systems being further condensed, e.g. 2,3-condensed with an oxygen-, nitrogen- or sulfur-containing hetero ring
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P31/00—Antiinfectives, i.e. antibiotics, antiseptics, chemotherapeutics
  • A61P31/04—Antibacterial agents

Definitions

• the present invention is directed to new cephem derivatives represented by the general formula in which the Acyl substituent is a group of the formula where Ar is an optionally substituted lipophilic phenyl, naphthyl, pyridyl or benzthiazolyl group, R 1 is selected from certain optionally substituted aliphatic, aromatic, arylaliphatic or sugar moieties and R 2 and R 3 are each independently hydrogen, alkyl or aminoalkylcarbonylamino.
• the derivatives are gram-positive antibacterial agents, especially useful in the treatment of diseases caused by methicillin-resistant Staphylococcus aureus (also referred to below as MRSA or methicillin-resistant S. aureus ).
• U.S. Patent 4,056,676 discloses cephem derivatives of the general formula where Z is hydrogen or fluorine; and when Z is hydrogen, each of X and Y is hydrogen or chlorine selected so that the phenyl ring is substituted with 1 or 2 chlorine atoms and so that when one chlorine atom is present said chlorine atom is in the 3-position, and when two chlorine atoms are present said chlorine atoms are in the 3,4-, the 3,5-or the 2,5-positions; and when Z is fluorine, said fluorine is in the 3- or 4-positions of the phenyl ring and each of X and Y is hydrogen or chlorine selected so that when the phenyl ring is substituted with 1 or 2 chlorine atoms, one of the chlorine atoms is in the 3- or 4-position of the phenyl ring; R 1 is hydrogen, dicyclohexylamine, or a pharmaceutically acceptable cation; and R is, inter alia , N-pyridino.
• the compounds specifically disclosed are those
• cephalosporin derivative of the formula is disclosed in Antimicrobial Agents and Chemotherapy - 1966 , pg. 573-580 at page 576 (Compound No. 48).
• U.K. Patent 998,265 discloses cephem derivatives of the general formula in which R 1 , taken alone, is -OH, C 1 -C 8 acyloxy, or tertiaryamino, R 2 is -OH when R 1 is -OH, R 2 is -OH when R 1 is C 1 -C 8 acyloxy, R 2 is -O- when R 1 is tertiaryamino, R 1 and R 2 , when taken together, are -O-, R 3 and R 4 represent hydrogen, alkyl radicals having from 1 to 6 carbon atoms, alkenyl radicals having from 2 to 6 carbon atoms, cycloalkyl radicals having from 5 to 7 carbon atoms, or alkoxyalkyl radicals having from 2 to 6 carbon atoms; n represents 0 to 4; and R 5 represents an alkyl radical having from 1 to 6 carbon atoms, an alkenyl or alkynyl radical having from 2 to 6 carbon atoms,
• U.K. Published Application No. 2,007,221 A discloses cephalosporin derivatives of the formula wherein Y is hydrogen, chlorine, bromine, C 1 -C 4 alkyl or C 1 -C 4 alkoxy; Z is a bond, oxygen or sulfur; W is hydrogen, methyl, amino, hydroxy, SO 3 H or COOR 4 wherein R 4 is hydrogen or 5-indanyl with the proviso that when Z is oxygen or sulfur, W is other than hydroxy; R 1 is hydrogen or methoxy; R 2 is hydrogen, acetoxy, 1,3,4-thiadiazol-2-ylthio, 5-methyl-1,3,4-thiadiazol-2-ylthio, tetrazol-5-ylthio, 1-methyltetrazol-5-ylthio, 1,3,4-oxadiazol-2-ylthio, 5-methyl-1,3,4-oxadiazol-2-ylthio, 1,3,4-triazol-2-ylthio, 5-methyl-1,3,4-triazol-2-
• U.S. Patent 3,217,000 discloses cephem derivatives of the formula wherein Thi is 2-thienyl or 3-thienyl and R is a substituent at the 3 or 4 position of the pyridino ring selected from the group consisting of cyano, carboxy, carbamyl, N-methylcarbamyl, carbo(C 1 -C 4 alkoxy), hydroxy and (C 1 -C 4 )alkanoyl; and the salts thereof with pharmaceutically acceptable acids.
• U.S. Patent 4,758,557 discloses cephalosporin derivatives of the general formula wherein A represents an alkanoyloxy group having 2-5 carbon atoms; a carbamoyloxy group; an azido group; or an unsubstituted or substituted pyridylthio group of the formula where n is 0 or an integer of 3-5; R 1 and R 2 may be the same or different and each represents a hydrogen atom, a halogen atom, a carboxyl group or an optionally halogen-substituted lower-alkyl group having 1-5 carbon atoms; or an unsubstituted or substituted pyridiniumthio group of the formula where n, R 1 and R 2 have the same meanings as above; R 3 represents a linear or branched-chain alkyl group having 1-5 carbon atoms, a halogen-substituted alkyl group, a cyclopropyl group, a cyclopropylmethyl
• U.S. Patent 4,786,633 discloses cephalosporin derivatives of the formula wherein R 2 is a substituted or unsubstituted heterocyclic group having 1-3 hetero atoms selected from the group consisting of nitrogen and sulfur.
• the R 2 group may be, for example, a group of the formula where R 4 is lower alkenyl, lower alkyl, or a lower alkyl group substituted with a carbamoyl group and R 5 and R 6 are the same or different and each represent hydrogen or lower alkyl.
• the present invention provides a novel series of cephem derivatives of the general formula wherein Ar is an aryl group selected from the group consisting of and in which R 4 , R 5 , and R 6 are each independently hydrogen, halogen, trihalomethyl, nitro, C 1 -C 6 alkyl, -(CH 2 ) n OR 7 or -(CH 2 ) n SR 7 ; n is an integer of from 1 to 6; R 7 is hydrogen or C 1 -C 6 alkyl; R 1 is selected from the group consisting of -CR 8 R 9 R 10 , -(CH 2 ) n CONR 8 R 9 and -(CH 2 ) n COR 8 in which R 8 , R 9 and R 10 are each independently hydrogen, substituted or unsubstituted C 1 -C 15 alkyl, C 2 -C 15 alkenyl or C 2 -C1 5 alkynyl, substituted or unsubstituted phenyl, phenyl(C 1
• the present invention provides novel cephem derivatives of general formula I above which are antibacterial agents useful in the treatment of infectious diseases in humans and other animals.
• the compounds exhibit good activity against a variety of gram-positive microorganisms, e.g. S. pneumoniae , S. pyrogenes , S. aureus , E. faecalis , E. faecium , S. epidermidis and S. hemolyticus , and are particularly useful against strains of methicillin-resistant S. aureus .
• the compounds of formula I are characterized by a substituted pyridiniumthiomethyl group of the type at the 3-position of the cephem ring and a lipophilic 7-substituent of the type wherein Ar is an aromatic group selected from optionally substituted phenyl, naphthyl, pyridyl or benzthiazolyl.
• salts as used herein is intended to include the nontoxic acid addition salts with inorganic or organic acids, e.g. salts with acids such as hydrochloric, phosphoric, sulfuric, maleic, acetic, citric, succinic, benzoic, fumaric, mandelic, p-toluenesulfonic, methanesulfonic, ascorbic, lactic, gluconic, trifluoroacetic, hydroiodic, hydrobromic, and the like.
• acids such as hydrochloric, phosphoric, sulfuric, maleic, acetic, citric, succinic, benzoic, fumaric, mandelic, p-toluenesulfonic, methanesulfonic, ascorbic, lactic, gluconic, trifluoroacetic, hydroiodic, hydrobromic, and the like.
• acids such as hydrochloric, phosphoric, sulfuric, maleic, acetic, citric, succinic,
• alkali metal salts particularly sodium or potassium
• alkaline earth metal salts particularly calcium or magnesium
• suitable organic bases such as lower alkylamines (methylamine, ethylamine, cyclohexylamine, and the like) or with substituted lower alkylamines (e.g. hydroxyl-substituted alkylamines such as diethanolamine, triethanolamine or tris- (hydroxymethyl) aminomethane), or with bases such as piperidine or morpholine, are also intended to be encompassed by the term "pharmaceutically acceptable salt".
• X ⁇ represents X the acid anion and R 11 is hydrogen or a carboxyl-protecting group.
• the counter anion X ⁇ may be selected so as to provide pharmaceutically acceptable salts for therapeutic administration.
• the carboxyl-protecting group R 11 is intended to include readily removable ester groups which have been employed to block a carboxyl group during the reaction steps used to prepare compounds I and which can be removed by methods which do not result in any appreciable destruction of the remaining portion of the molecule, e.g. by chemical or enzymatic hydrolysis, treatment with chemical reducing agents under mild conditions, irradiation with ultraviolet light or catalytic hydrogenation, etc.
• protecting groups include benzhydryl, p-nitrobenzyl, 2-naphthylmethyl, allyl, benzyl, p-methoxybenzyl, trichloroethyl, silyl such as trimethylsilyl, phenacyl, acetonyl, o-nitrobenzyl, 4-pyridylmethyl and C 1 -C 6 alkyl such as methyl, ethyl or t-butyl.
• protecting groups include those which are hydrolyzed under physiological conditions such as pivaloyloxymethyl, acetoxymethyl, phthalidyl, indanyl, ⁇ -acetoxyethyl, ⁇ -pivaloyloxyethyl, and methoxymethyl.
• Compounds of formula I with such physiologically hydrolyzable carboxyl protecting groups are also referred to herein and in the claims as "prodrugs".
• Compounds of formula I where R 11 is a physiologically removable protecting group are useful directly as antibacterial agents.
• Compounds where an R 11 protecting group is not physiologically removable are useful intermediates which can be easily converted to the active form by conventional deblocking procedures well-known to those skilled in the art.
• a preferred embodiment of the present invention comprises compounds of formula I wherein Ar is in which R 4 , R 5 and R 6 are each independently hydrogen, halogen, trifluoromethyl or C 1 -C 6 alkyl.
• R 1 is -CR 8 R 9 R 10 in which R 8 , R 9 and R 10 are each independently hydrogen, C 1 -C 6 alkyl, hydroxy(C 1 -C 6 )alkyl, C 2 -C 6 alkenyl, phenyl(C 1 -C 6 )alkyl, hydroxyphenyl(C 1 -C 6 )alkyl or dihydroxyphenyl(C 1 -C 6 )alkyl; R 2 and R 3 are each independently hydrogen, C 1 -C 6 alkyl or amino(C 1 -C 6 )alkylcarbonylamino; or a pharmaceutically acceptable salt or prodrug thereof.
• the most preferred compounds are those in which Ar is in which R 4 , R 5 and R 6 are each independently hydrogen, halogen, trifluoromethyl or C 1 -C 6 alkyl.
• Another preferred embodiment comprises the compounds of formula I wherein the 3-substituent has the formula wherein R 1 is -(CH 2 ) n CONR 8 R 9 in which R 8 and R 9 are each independently hydrogen, hydroxy(C 1 -C 6 )alkyl, n is an integer from 1 to 6; and R 2 and R 3 are each independently hydrogen, C 1 -C 6 alkyl or amino(C 1 -C 6 )alkylcarbonylamino; or a pharmaceutically acceptable salt or prodrug thereof.
• the most preferred compounds are those in which Ar is in which R 4 , R 5 and R 6 are each independently hydrogen, halogen, trifluoromethyl or C 1 -C 6 alkyl.
• Another preferred embodiment comprises the compounds of formula I wherein the 3-substituent has the formula wherein R 1 is -(CH 2 ) n COR 8 in which R 8 is C 1 -C 6 alkyl; n is an integer of from 1 to 6; and R 2 and R 3 are each independently hydrogen, C 1 -C 6 alkyl or amino(C 1 -C 6 )alkylcarbonylamino; or a pharmaceutically acceptable salt or prodrug thereof.
• the most preferred compounds are those in which Ar is in which R 4 , R 5 and R 6 are each independently hydrogen, halogen, trifluoromethyl or C 1 -C 6 alkyl.
• Another preferred embodiment comprises the compounds of formula I wherein the 3-substituent has the formula wherein R 1 is R 2 and R 3 are each independently hydrogen, C 1 -C 6 alkyl or amino(C 1 -C 6 )alkylcarbonylamino; or a pharmaceutically acceptable salt or prodrug thereof.
• R 1 is R 2 and R 3 are each independently hydrogen, C 1 -C 6 alkyl or amino(C 1 -C 6 )alkylcarbonylamino; or a pharmaceutically acceptable salt or prodrug thereof.
• the most preferred compounds are those in which Ar is in which R 4 , R 5 and R 6 are each independently hydrogen, halogen, trifluoromethyl or C 1 -C 6 alkyl.
• the compounds of the present invention can be made by conventional methods. Two suitable procedures are summarized by the following reaction scheme:
• thiol VII is converted into the arylthioacetic acid derivative VI, e.g. by treatment with bromoacetic acid under basic conditions (e.g. aqueous sodium or potassium hydroxide).
• the reaction temperature for this step is typically between 20° and 100°C.
• Starting thiol VII is commercially available or can be prepared according to known literature procedures.
• the product VI is typically isolated by crystallization or, if necessary, it can be purified by chromatography.
• Arylthioacetic acid VI is then coupled with a suitable cephem intermediate having a suitable 3-substituent leaving group.
• the leaving group may be acetoxy or halo.
• the cephem intermediate is the 3-chloromethyl cephem V, but other suitable cephem intermediates with equivalent leaving groups at the 3-position could also be employed.
• the cephem intermediate V may be acylated with VI or a reactive derivative thereof by conventional acylation procedures well-known in the cephalosporin art to give N-acylated intermediate IV.
• the free arylthioacetic acid e.g.
• acylating agent VI may also be employed in the form of equivalent acylating derivatives such as an acid anhydride, mixed anhydride, activated ester or acid halide.
• the cephem intermediate preferably has the carboxyl group protected by a conventional carboxyl-protecting group which can be readily removed. Examples of such protecting groups are discussed above and include benzyl, 4-nitrobenzyl, 4-methoxybenzyl, diphenylmethyl, allyl, and the like. Other examples of suitable protecting groups are disclosed in Protective Groups in Organic Synthesis , Theodora W. Greene (John Wiley & Sons, 1981), Chapter 5.
• intermediate V may be acylated with acid VI in the presence of dicyclohexylcarbodiimide and in an inert solvent such as tetrahydrofuran or dichloromethane.
• the reaction temperature is typically between -20°and 50°C.
• insoluble material is removed by filtration, the filtrate is concentrated, and the residue is treated with a relatively non-polar solvent such as diethyl ether or ethyl acetate resulting in precipitation of the desired product.
• acid VI may be converted to the corresponding acid chloride, for example by treatment with thionyl chloride with or without a solvent such as dichloromethane, followed by coupling with cephem amine V in the presence of a base such as triethylamine or N-methylmorpholine to give intermediate IV.
• Cephem IV is typically isolated by aqueous workup followed by trituration of the compound with a relatively non-polar solvent such as diethyl ether or ethyl acetate.
• Conversion of cephem IV to the target quaternary cephems I may be accomplished by two different methods.
• One method entails displacement of an appropriate 3-substituent leaving group with 4-mercaptopyridine followed by quaternization of the pyridyl nitrogen, followed by deprotection of the cephem carboxylate ester.
• the iodide is typically used without purification.
• alkylating agents are primary alkyl halides such as methyl iodide, allylic halides such as allyl bromide, halomethyl ethers such as chloromethyl methyl ether and ⁇ -halocarbonyl derivatives such as iodoacetamide and 1-bromoacetone.
• the alkylation reaction is carried out in an inert solvent such as acetone, dimethylformamide or tetrahydrofuran and is run at temperatures between -20° and 100°C. Removal of the cephem carboxylate ester protecting group to give I is then accomplished under acidic conditions.
• R is diphenylmethyl or 4-methoxybenzyl
• I is obtained upon treatment of I' with trifluoroacetic acid neat or in an inert solvent such as methylene chloride.
• a reagent such as anisole may also be employed to scavenge the liberated ester protecting group.
• the deprotection may also be carried out by treatment with other protic acids such as hydrochloric acid in a solvent such as methanol.
• the final product is typically isolated by precipitation or crystallization.
• cephem I is purified by column chromatography, for example on reversed-phase adsorbent.
• intermediate IV is deprotected under acidic conditions, followed by reaction of the resulting intermediate IV' with a thiopyridone derivative III.
• R is diphenylmethyl or 4-methoxybenzyl
• treatment of cephem intermediate IV under acidic conditions as described above provides cephem acid IV'.
• Reaction of IV' with a thiopyridone derivative III in a solvent such as dimethylformamide, dimethyl sulfoxide, ethanol, methanol, or other appropriate solvents at a temperature between -20° and 100°C affords target quaternary cephem I.
• Thiopyridones III are typically prepared according to a method analogous to that described in T.
• the product may be isolated as its sodium salt by evaporation of volatile solvents, followed by trituration with a solvent such as diethyl ether or ethyl acetate.
• the reaction mixture may be acidified and extracted with an organic solvent to afford the product as the free carboxylic acid.
• the carboxylate group is protected as an ester, the amine may be free or present as an acid salt.
• a base such as sodium hydroxide, sodium bicarbonate or pyridine is added to form the free amine in situ.
• the product is typically isolated by precipitation or by reversed phase column chromatography following removal of volatile solvents.
• thiopyridone derivatives of formula III are novel compounds and are intended to be a further aspect of the present invention.
• the following compounds are encompassed by the present invention:
• the desired end-product of formula I may be recovered either as the zwitterion or in the form of a pharmaceutically acceptable acid addition salt, e.g. by addition of the appropriate acid such as HCl, HI or methanesulfonic acid to the zwitterion.
• a pharmaceutically acceptable acid addition salt e.g. by addition of the appropriate acid such as HCl, HI or methanesulfonic acid to the zwitterion.
• Compounds of formula I where R 11 is hydrogen or an anionic charge, or a pharmaceutically acceptable salt thereof may be converted by conventional procedures to a corresponding compound where R 11 is a physiologically hydrolyzable ester group.
• novel cephalosporin derivatives of general formula I wherein R 11 is hydrogen, an anionic charge or a physiologically hydrolyzable carboxyl-protecting group, or the pharmaceutically acceptable salts or prodrugs thereof are potent antibiotics active against many gram-positive bacteria. While they may be used, for example, as animal feed additives for promotion of growth, as preservatives for food, as bactericides in industrial applications, for example in waterbased paint and in the white water of paper mills to inhibit the growth of harmful bacteria, and as disinfectants for destroying or inhibiting the growth of harmful bacteria on medical and dental equipment, they are especially useful in the treatment of infectious disease in humans and other animals caused by the gram-positive bacteria sensitive to the new derivatives. Because of their excellent activity against MRSA organisms, they are particularly useful in the treatment of infections resulting from such bacteria.
• compositions comprising, in addition to the active cephem ingredient, a pharmaceutically acceptable carrier or diluent.
• the compounds may be administered by a variety of means, for example, orally, topically or parenterally (intravenous or intramuscular injection).
• the pharmaceutical compositions may be in solid form such as capsules, tablets, powders, etc. or in liquid form such as solutions, suspensions or emulsions.
• Compositions for injection, the preferred route of delivery may be prepared in unit dose form in ampules or in multidose containers and may contain additives such as suspending, stabilizing and dispersing agents.
• the compositions may be in ready-to-use form or in powder form for reconstitution at the time of delivery with a suitable vehicle such as sterile water.
• the dosage to be administered depends, to a large extent, on the particular compound being used, the particular composition formulated, the route of administration, the nature and condition of the host and the particular situs and organism being treated. Selection of the particular preferred dosage and route of application, then, is left to the discretion of the physician or veterinarian. In general, however, the compounds may be administered parenterally or orally to mammalian hosts in an amount of from about 50 mg/day to about 20 g/day. Administration is generally carried out in divided doses, e.g., three to four times a day, analogous to dosing with a cephalosporin such as cefotaxime.
• MIC Minimum Inhibitory Concentrations
• NCLS National Committee for Clinical Laboratory Standards
• Mueller-Hinton medium was used except for Streptococci which was tested in Todd Hewitt broth.
• the final bacterial inoculate contained approximately 5 x 10 5 cfu/ml and the plates were incubated at 35°C for 18 hours in ambient air (Streptococci in 5% CO 2 ).
• the MIC was defined as the lowest drug concentration that prevented visible growth.
• Organisms The test organism, MRSA strain A27223 used to generate systemic infection in mice, is grown on two large Brain Heart Infusion Agar plates. On each plate, 0.5 ml of frozen stock culture is plated out. Plates are then incubated for 18 hours at 30°C. The next day each plate is washed with 20 ml of Brain Heart Infusion Broth and then pooled together. A microscopic direct count of microorganism is done using a 1:1000 dilution of plate wash. After a direct count is obtained, the number of organisms per milliliter is calculated. The count is adjusted to the desired amount of inoculum by diluting in 4% hog mucin.
• the desired challenge (amount of organisms given to mice) is 2.4 x 10 8 cfu/0.5 ml/mouse for MRSA strain A27223.
• the mice are infected intraperitoneally with 0.5 ml of challenge.
• Ten non-treated infected mice are used as controls.
• mice Mice used are male ICR mice. The average weight of the animals is from 20 to 26 grams.
• Drug preparation and treatment Compounds are tested at 4 dose levels, (25, 6.25, 1.56, and 0.39 mg/kg) and prepared in 5% cremophor, unless otherwise specified. Vancomycin is used as the control compound, and is dosed at 6.25, 1.56, 0.39, and 0.098 mg/kg. It is prepared in 0.1M phosphate buffer. There are five infected mice per dose level, and they are treated with 0.2 ml of the test compound, preferably by intramuscular injection. Treatment begins 15 minutes and 2 hours post-infection.
• Test duration A PD 50 (the dose of drug given which protects 50% of mice from mortality) runs for 5 days. During this time, mortality of mice are checked every day and deaths are recorded. The cumulative mortality at each dose level is used to calculate a PD 50 value for each compound. Surviving mice are sacrificed at the end of day 5 by CO 2 inhalation.
• results The in vivo efficacy, expressed as the PD 50 value, ranged from about 0.6 to about 22 mg/kg (for certain compounds, more than one test was carried out; the indicated range is for at least one test result when multiple tests were done).
• Splitting patterns are designated as follows: s, singlet; d, doublet; t, triplet; q, quartet; m, multiplet; br, broad peak; dd, doublet of doublets and dt, doublet of triplets.
• Infrared spectra were determined on a Perkin-Elmer 1800 FT-IR spectrometer from 4000 cm -1 to 400 cm -1 , calibrated to 1601 cm -1 absorption of a polystyrene film, and are reported in reciprocal centimeters (cm -1 ).
• Mass spectra were recorded on a Kratos MS-50 or a Finnegan 4500 instrument utilizing direct chemical ionization (DCI, isobutene) or fast atom bombardment (FAB).
• Ultraviolet spectra were determined on a Hewlett Packard 8452 diode array spectrophotometer in the solvent indicated.
• Analytical thin-layer chromatography was carried out on precoated silica gel plates (60F-254) and visualized using UV light, iodine vapors, and/or staining by heating with methanolic phosphomolybdic acid.
• Column chromatography also referred to as flash chromatography, was performed in a glass column using finely divided silica gel at pressures somewhat above atmospheric pressure with the indicated solvents.
• Reversed-phase analytical thin-layer chromatography was carried out on precoated reverse phase plates and visualized using UV light or iodine vapors.
• Reversed-phase column chromatography was performed in a glass column using Baker Octadecyl (C 18 ), 40 ⁇ m.
• Method a A solution of 2,5-dichlorophenylthioacetic acid (13.0 g, 54.9 mmol) in methylene chloride (55 mL) and thionyl chloride (10 mL, 137 mmol) was heated at reflux for 3 h. The reaction mixture was allowed to cool to room temperature and was concentrated in vacuo. The residue was evaporated two times from toluene to give 14 g of 2,5-dichlorophenylthioacetyl chloride (100 % yield) as a slightly colored product which was used in the next step without purification.

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• 1995
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